# copyright (c) 2024 PaddlePaddle Authors. All Rights Reserve.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import re
from typing import Union


def parse_scale(s: Union[float, str]) -> float:
    if isinstance(s, float):
        return s
    if re.fullmatch(r"1(?:\.|\.0)?\s*/\s*255(?:\.|\.0)?", s):
        return 1 / 255
    else:
        raise ValueError("Invalid scale")
